Aspirin, also known as acetylsalicylic acid, was first synthesized in 1853 and applied in clinical treatments in 1899. Aspirin has a variety of pharmaceutical efficacies, and aspirin can have an effect of alleviating headache in a short term by angiectasis, and can be therefore used for analgesia and antipyresis. Aspirin is the first choice drug for the treatment of rheumatic fever, and after administration, antipyresis and inflammation reduction can be achieved, such that articular symptoms are improved, and the erythrocyte sedimentation rate is reduced. In addition to rheumatoid arthritis, the product is also used for treating rheumatoid arthritis, can improve symptoms, and create conditions for a further treatment. In addition, aspirin is used for musculoskeletal pain disease of osteoarthritis, ankylosing spondylitis, juvenile arthritis and other non-rheumatic inflammations, and can also relieve symptoms. Aspirin has an inhibiting effect on platelet aggregation and can thus prevent thrombosis, and clinically, aspirin can be used for preventing transient ischemic attack, myocardial infarction, atrial fibrillation, cardiac valve prosthesis or other postoperative thrombosis, and can also be used for treating unstable angina pectoris. Aspirin can also be used for reducing mucocutaneous lymphnode syndrome (Kawasaki disease). It is also found from studies that aspirin works in terms of the prevention of colon cancer, rectal cancer, esophageal cancer, etc. Therefore, the therapeutic use of aspirin is very valuable.
However, the oral administration of aspirin tends to result in gastrointestinal adverse reactions. The most major reactions include indigestion, stomach and duodenal hemorrhages, gastric ulcer, gastritis and other symptoms. Therefore, researchers have been trying all the time to study aspirin derivatives of other administration routes, in order to reduce or avoid the gastrointestinal adverse reactions caused by the oral administration of aspirin.
Chinese patent CN 101484415 B discloses a water-soluble aspirin prodrug (an acetylsalicylic acid derivative), and in the treatment, the prodrug may be administered transdermally into the body, avoiding the gastrointestinal adverse reactions caused by the common oral administration of aspirin.
However, the above-mentioned patent does not disclose any compound crystal form of the water-soluble aspirin prodrug. The study of solid drug crystal form facilitates the control of the stability of the drug during preparation and storage. The determination of a preparation process according to the characteristics of a crystal form to improve the performance of a solid pharmaceutical preparation can effectively ensure the drug inter-batch equivalence in production. Therefore, obtaining the crystal form of the compound is an important measure to ensure the quality of the drug.